Door & Window Contact Sensor: This SECRUI magnetic door & window chime alarm sensor will emit loud volume alarm of 130dB when the door is suddenly open. It can prevent your kids from sneaking out. And its a perfect wireless security magnetic alarm for kids' safety, anti-theft, home, garage, postbox, and business' security. 4 Alarm Modes: It has 4 types of alarm modes-- 1 Ordinary alarm mode (Alarm will last for 1 minute if your door is being open); 2 Wireless Doorbell mode (Ding dong, rings once as a welcome tone ); 3 Alarm and Stop mode (It will alarm loudly if the door is open, and it will stop as soon as your door is closed); 4 Door closing reminder mode ("Di Di", from low to high, it will remind you by repeated sound until the door is closed). Easy to Install: This home/window contact sensor alarm security kit come with self adhesive pads so no tools are required, just had to stick the door alarm sensor on the door or window. It can also be used as a doorstop alarm, pool door alarm, garage door alarm or sliding door alarm. Fast Automatic Switch: With ultra-sensitive magnetic sensor desgin, this contact sensor kit can quickly detect your door or windows' status. It's powered by 2*AAA battery (Not included).